“We’re extremely grateful and overwhelmed by everyone’s kindness, gratitude and generosity,” his widow, Pei Xia Chen, said at a news conference outside her Gravesend, Brooklyn, house on what would have been Liu’s 33rd birthday.

Investigators say Brinsley was an emotionally disturbed loner who had made references online to the killings this summer of unarmed black men — including Eric Garner on Staten Island — at the hands of white police officers, vowing to put “wings on pigs.”

The Stephen Siller Tunnel To Towers Foundation, named for a firefighter killed on 9/11, collected more than $1 million in donations from across the country and other parts of the world in an effort to pay off the families’ home mortgages.